Technical Abstract:
Research in cold plasma processing at the USDA’s Eastern Regional Research Center is focused on developing this technology into an effective tool to improve the safety of a variety of foods. Cold plasma applied to outbreak strains of Escherichia coli O157:H7 and Salmonella Stanley inoculated on the surfaces of golden delicious apples resulted in significant (p<0.05) reductions from the untreated control. Maximum reductions were obtained after 180 seconds of treatment, and ranged from 2.9 to 3.7 log cfu/ml for S. Stanley, and 3.4 - 3.6 log cfu/ml for E. coli O157:H7. Inactivation followed a time-dependent reduction when plasma was applied at different flow rates of the feed gas. Temperature increase of the treated apples was also related to exposure time for all flow rates. The maximum temperature of any plasma treated apple was 50.8C (28C above ambient), indicating that antimicrobial effects were not the result of heat. A more advanced form of the arc discharge reduced Salmonella and E. coli O157:H7 on agar plates by approximately 1 log cfu in 10 seconds. This presentation will provide a status summary of ongoing research at the USDA labs, and discuss future applications of this technology.